The genes coding for the alcohol dehydrogenase (ADH) isozymes of the yeast Saccharomyces cerevisia will be studied by a variety of techniques. Assays for the mRNA based on in vitro translation have been developed and used to distinguish between ADH I and II. We have cloned the gene for ADH I and will study its sequence. This DNA will serve as a probe for mRNA synthesis and isolation of the genes for other ADH isozymes. The effect of various mutations on the levels of ADH mRNA and proteins will be characterized in an effort to understand the regulation of ADH gene expression.